1. Field of the Invention
The present invention relates to a mirror device for a vehicle which is provided at a vehicle.
2. Description of the Related Art
A door mirror device for a vehicle is provided with, for example, a retracting mechanism. The retracting mechanism has a stand. The stand is fixed, via a stay, to a door of the vehicle. A supporting shaft is provided integrally with the stand so as to stand upright.
The retracting mechanism has a case member. The case member is formed in the shape of a box whose top surface is open. The case member is supported so as to be freely rotatable around the supporting shaft in a state in which the supporting shaft is inserted in the case member. The case member is connected to a mirror for viewing the region substantially at the rear of the vehicle. The case member thereby always pivots integrally with the mirror.
A motor base member is press-fit into the opening at the top surface of the case member, so as to be assembled together with the case member. The motor base member pivots together with the case member. A motor is set at the motor base member.
A twin gear spans between the bottom wall of the case member and the motor base member, so as to rotate freely. The twin gear is a first gear and a second gear which always rotate integrally. The first gear of the twin gear meshes intermittently with the driving shaft of a motor. The twin gear is thereby rotated by the driving of the motor.
Within the case member, the supporting shaft is inserted through an output gear in a state in which rotation of the output gear is impeded. The output gear meshes with the second gear of the twin gear. In this way, when the twin gear rotates, the twin gear moves around the periphery of the output gear. Thus, the case member and the motor base member pivot around the supporting shaft, and the mirror is retracted or extended.
However, in this door mirror device for a vehicle, the motor base member is assembled in merely by being press-fit into the opening at the top surface of the case member. Thus, if impacts are repeatedly applied from the exterior to the retracting mechanism (in particular, the opening at the top surface of the case member or the motor base member) or if the operations of retracting the mirror and extending the mirror are repeated, the force of anchoring the motor base member by the case member is reduced.
In this way, when the mirror is retracted or extended, the motor base member sways (rocks) with respect to the case member, and the twin gear tilts. Thus, the meshing of the output gear and the second gear of the twin gear may become unstable, and the operation of retracting the mirror or the operation of extending the mirror may become unstable. In particular, at the time of completion of retracting of the mirror or at the time of completion of extending of the mirror, it is easy for the motor base member to sway, with respect to the case member, mainly in a direction perpendicular to a central perpendicular line (a line perpendicular to the central axis of the supporting shaft and to the central axis of the twin gear). Thus, it is easy for the meshing of the output gear and the second gear of the twin gear to become unstable at the time when retracting of the mirror starts or extending of the mirror starts.